We found an extensive bed of Rissoides desmaresti
in June 1999 off Pwllheli/Abersoch during some of our SAC monitoring surveys
- it was one of the first diver-observed beds in the UK. The bed was estimated
to cover 62 acres at the north end of Cardigan Bay. There are
dense concentrations of them off the east side of the East St Tudwall Island
just off Abersoch. We also found them off Pwllheli.

Not in the Books

In view of the large numbers that we discovered,
it was surprising to note they are not listed in any of the identification
guides as a British species.

British Distribution

From
evidence of plankton trawls of the larvae, Rissoides desmaresti
occurs sporadically around the British coast. However, before this bed
was discovered there was not a single confirmed report of the adults. Moderate
numbers of larvae have been found in the planktonic stage, enough to constitute
a British species but not enough for the identification guides. There is
possibly a population of them somewhere off the Isle of Wight and perhaps
around the Plymouth area too (Keith Hiscock mentioned fishermen bringing
them ashore in cod stomachs), although I know of no other diver observations
from anywhere in the country.

Bionomics

The Mantis Shrimps were about 10 cm long. And
the numbers were surprising, roughly 1 per square metre over an area
of about 0.25 square km (25 hectares, 62 acres), thinning out to around
1 burrow per 100 square metres. i.e. 250,000 plus.

Burrows

In the densest part of the vast bed, the burrows
were easily recognisable and distinguishable from those of the Burrowing
Prawn Upogebia.

The U-shaped burrows had an entrance about 3 cm
across. The exit to the burrow was much smaller and inconspicuous.
It was only noticeable when we tried to catch the shrimps, as they use
this as an escape route. The bottom of the 'U' flattened off about
15 cm below the surface. The burrows were at a depth of about 8-15 metres
below Chart Datum, in sediment comprising
of muddy shelly gravel and sand with a sparse scattering of maerl and whole
shells.

By approaching the burrows very carefully you
occasionally get a glimpse of the Mantis Shrimp sitting a few centimetres
down its burrow. Catching them can be a painful experience - not
only is the front end particularly well armed (they have a single serrated
digit similar to a preying mantis) but the telson is also heavily spined
and they use this to stab you repeatedly in the fingers!

Although
the report of the Mantis Shrimps actually dated from June 1999, this report
was so unusual that I did not include it immediately in this newsletter
or the Torpedo Electronic Bulletins. AH.

The
identification by Rohan Holt was confirmed by Roger Bamber.

11
February 2016A
12 cm long Mantis Shrimp, Rissoides
desmaresti, was washed ashore on the
Kent coast. This is the first known record from Kent. The discovery was
made at Greatstone
on the English Channel coast.

6
February 2014Scores
of Mantis Shrimps, Rissoides
desmaresti, were washed ashore at Felpham,
near Bognor Regis,
West Sussex. They were discovered by Mike
Burgess on the strandline.
The records from this area were only in ones or twos before.

Report
and Photograph by Mike Burgess

c 5 December 2009

A Mantis Shrimp,
Rissoides
desmaresti, was found in the stomach of a Pouting caught
two miles east of the Isle of Wight. The Mantis Shrimp was a little over
four inches (just over 10 cm) in length.

Vin
Lam Photographson flickrMarlin
Information Page on the Mantis ShrimpIn April 2000, Bernard
Roberts on the fishing vessel "Avanti" reported Dogfish, Scyliorhinus
canicula, eating a couple of Mantis Shrimps one mile east of Pwllheli
Harbour.
July 2000Just returned from a resin casting trip - got
5 good casts that show how the burrows are shaped.Elongated U shaped as suspected, going down no
more than about 15 cm and fairly uniform throughout (about 2.5 cm diam).
However, all casts show a distinct constriction around about the mid-point
of the burrow where thediameter reduces to about 1.5 cm. Is this
a common burrowing shrimp/mantis shrimp feature????? Pics of the
casts will be ready soonish.All the bestRohan
Mauchline's (1984)
"Euphausiid, Stomatopod, and Leptostracan Crustaceans" in the SYNOPSES
OF THE BRITISH FAUNA (NEW SERIES) no. 30, contains several localities for
R.
desmaresti, albeit under the old name Meiosquilladesmaresti. (from
Frederik
R. Schram, Professor of Systematics and Zoogeography Zoological Museum,
University of Amsterdam)Trevor Bull reported
trawling large amounts of Mantis shrimps, Rissoides
desmaresti, circa 1984-85
in the Plemont deep (NW Jersey coast), also large amounts of very small
spider crabs, Maja squinado (body the size
of a golfball.
He also found a few two miles north of Les
Bouefs (tower several miles to the SE of Jersey).
Les Bouefs is reputed to be the site where one crossed to France
across a plank, before the sea level rose.

June 2001A Mantis Shrimp,
Rissoides
desmaresti, has been found in Lyme Bay.
The specimen was captured by a local fishermen in a trawl net. The specimen
was around 85 mm and was captured with a good haul of cod which were feeding
upon the mantis shrimps.